A witness, 18, who did not want to be named, said: “Four guys pulled up in a car, jumped out and attacked the group. They had hoodies pulled down and bandanas covering their faces. It seemed to be over really quickly and the others had no time to fight back."

A Met police spokesman added: "Officers attended and found three males believed to be aged in their twenties suffering from stab injuries.

"Two of the males have been taken to hospital in a serious condition.

"The third was treated at the scene for critical stab injuries.

TWITTER/SAMANTHA J BOOTH

STABBING: One victim banged on the doors of residents asking them to call 999